Stress corrosion crack propagation behavior in cold worked low-alloy steel SA508 in simulated primary water of PWR

Abstract

This study systematically investigates the stress corrosion crack growth rate (SCCGR) of SA508-Gr3 Cl.2 alloy, a pressure vessel steel for nuclear power plants, under varying cold working (CW) conditions (0 % CW, 10 % CW, 20 % CW, and 30 % CW) in simulated primary water environments. The results demonstrate a strong positive correlation between CW degree and SCCGR, with measured values of 1.81 × 10⁻⁸ mm/s (0 % CW), 3.39 × 10⁻⁸ mm/s (10 % CW), 4.78 × 10⁻⁸ mm/s (20 % CW), and 6.02 × 10⁻⁸ mm/s (30 % CW). Compared to the undeformed condition (0 % CW), the SCCGR increased by 87.29 %, 164 %, and 233 % for 10 % CW, 20 % CW, and 30 % CW, respectively. Furthermore, at 30 % CW, the SCCGR exhibited significant oxygen dependence, showing 88.70 % and 157 % increases at dissolved oxygen (DO) concentrations of 100 ppb and 500 ppb, respectively, relative to the low-oxygen condition (DO < 5 ppb). These findings provide critical insights into the synergistic effects of cold working and environmental factors on nuclear-grade pressure vessel steels' stress corrosion cracking behavior.